Device for inserting a continuous tape for a printing or copying system comprising modules

ABSTRACT

An apparatus and method is provided for threading a continuous web into a device arrangement having a first module and a second module connectable to and detachable from one another. First and second traction units are provided in the first and second modules. A gripper device grips a beginning section of the continuous web and is detachable to the traction units. The continuous web is pulled with the assistance of the gripper device from an input section to an output section of the respective module given movement of the traction units. A connector device connects the two traction units of the two modules to each other.

BACKGROUND OF THE INVENTION

The invention is directed to an apparatus for threading a continuousweb, whereby a gripper device transports the beginning section of thecontinuous web from an input section for the continuous web up to anoutput section. The invention is also directed to a printer or copiersystem as well as to a module. Further, the invention is directed to acombined monitoring device.

DE-A 198 01 317 of the same assignee discloses an apparatus forintroducing continuous stock recording media into electrographic printeror copier devices. This document is incorporated by reference as asource of disclosure for the present patent application. The assistanceof such an apparatus makes it possible to automatically thread acontinuous web through the printer machine before the beginning of aprinting process. The operating ease is enhanced in this way and theeconomic feasibility of the printing machine is improved.

EP-A-0 152 737 discloses a draw-in device for drawing a paper web to beprinted into a printing machine. In this printing machine, the tractionmeans for drawing the paper web in has a common path (A) and either anupper path (B) or a lower path (C). The traction means is connected attwo shunts to a traction means element for the upper path (B) or to atraction means element for the lower path (C).

High-performance printers and high-performance copiers that can handleextensive and complex print jobs or copier jobs are being employed to anincreasing extent. Such systems are relatively large in volume, so thatthey are resolved into a number of machine modules that are easy totransport. The various modules are connected at the user=s premises toform the printing system or copier system. For example, WO 98/39691 ofthe same assignee discloses such high-performance printer systems orcopier systems. This document is introduced by reference into thedisclosure of the present application.

Another advantage of a modular concept wherein, for example, a printingsystem is divided into a printer module and a fixing module is theenhanced flexibility. Thus, an existing printer module can be combinedwith various types of fixing modules, whereby a prerequisite therefor isa defined, common interface. In a further development of the modularconcept, modules processing further recording media can also be utilizedthat can be versatilely combined with further modules.

FP-60-99655 A with Abstract discloses an apparatus for drawing acontinuous paper web in, whereby this continuous paper web is pulledthrough a plurality of successively arranged device modules. Each devicemodule has its own traction means that circulates within the module.When the continuous web is conducted through a plurality of modules, thebeginning section of the paper web is handed over to the traction meansof the next module at the boundaries of the respective module.

SUMMARY OF THE INVENTION

An object of the invention is to specify an apparatus for threading acontinuous web that is constructed in a simple way and is simple tohandle and that works with high operating dependability.

According to the present invention, an apparatus and method are providedfor threading a continuous web into a device arrangement having a firstmodule and at least one second module connectable to and detachable fromone another at an interface and which are successively traversed by thecontinuous web. Respective first and second traction units withcorresponding drive units are provided in the first and second modules.The gripper device grips a beginning section of the continuous web andis attachable to the traction units, the continuous web being pulledwith the assistance of the gripper device from an input section to anoutput section of the respective module given movement of the tractionunits. A connector device is provided with which the traction units ofthe two modules residing opposite one another at the interface areconnectable to and detachable from one another. The gripper devicetransports a beginning section of the continuous web from the inputsection of the first module up to the output section of the secondmodule in the connected condition of the traction units.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a printing system with a knownintroduction device for introducing a continuous web;

FIG. 2 is an arrangement of a printing system with a printer module anda fixing module having an apparatus for threading the continuous web;

FIG. 3 is a schematic illustration of the interface between the twomodules and the connecting device;

FIG. 4 is a perspective illustration of the connecting device with thetwo crossbeams;

FIG. 5 is a perspective illustration of a tensing element with positiondetectors;

FIG. 6 is a schematic illustration of various states of the tensingelements;

FIG. 7 is an illustration of a combined monitoring device with twotensing devices;

FIG. 8 shows three operating conditions of the combined monitoringdevice;

FIG. 9 shows a schematic illustration of the regulation of the cabletension with the assistance of the combined monitoring device; and

FIG. 10 illustrates the realization of the combined monitoring deviceupon employment of compression springs.

DESCRIPTION OF THE PREFFERED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the preferred embodimentillustrated in the drawings and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the invention is thereby intended, such alterations andfurther modifications in the illustrated device, and/or method, and suchfurther applications of the principles of the invention as illustratedtherein being contemplated as would normally occur now or in the futureto one skilled in the art to which the invention relates.

According to the disclosed system, a traction unit is provided in eachmodule, the assistance of the traction units making it possible totransport a gripper device for gripping a beginning section of thecontinuous web from an input section up to an output section of therespective module. The two traction means reside opposite one another atthe interface between the two modules. A separable connecting deviceconnects the two traction units, so that a combined through tractionunit for both modules is created in the connected condition of thetraction unit, and the gripper device can transport the beginningsection of the continuous web from the input section of the first moduleup to the output section of the second module. The two traction unitscan in turn be detached from one another with the assistance of theconnecting device, so that the two modules can be transported to adifferent location separately from one another. An apparatus is thusprovided that allows an automatic threading of a continuous web throughtwo or more modules. The apparatus is simply constructed and requiresuncomplicated handling. When more than two modules are connected to oneanother, then a plurality of connecting devices that connect therespective traction units in the modules to one another are to beutilized at the module boundaries for creating a through traction units.

Another aspect is directed to a printer or copier system that isequipped with the described, modularly constructed threading apparatus.

According to a further aspect, a module is recited as part of a printeror copier system, whereby the module and a further module areconnectable to one another and detachable from one another at aninterface, comprising a traction unit with whose assistance a gripperdevice for gripping a beginning section of the continuous form can betransported from an input section up to an output section of the module,and comprising a part of a connecting device with which the tractionunits of the two modules residing opposite one another at the interfaceare connectable to one another and detachable from one another. When aplurality of modules are equipped with such a threading apparatus, thenthese modules can be connected to one another, as a result whereof anautomatic threading of a continuous web through the various modules isenabled.

A further aspect is directed to a combined monitoring device, wherebythe downward transgression of too low a tractive force of the tractionunit and an upward transgression of too high a tractive force of thetraction unit is signaled. With the assistance of combined monitoringdevice, the tension of the traction unit in the device arrangementcomprised of a plurality of modules can also be regulated in oneexemplary embodiment. The combined monitoring device contains a firsttensing device and a second tensing device that are respectively chargedby spring powers in the direction of the axis of the traction unit. Whena specific tractive force of the traction unit is downwardlytransgressed, the one tensing device is moved out of a limit position;when the tractive force of the traction unit is upwardly transgressed,the other tensing device is moved out of a limit position. A positionsensor detects the movement of the tensing devices out of the limitpositions and generates signals, whereupon the drive units for thetraction units can be deactivated.

An exemplary embodiment of a known printing system as well as anexemplary embodiment with an apparatus is explained below.

FIG. 1 shows a schematic side view of a printing system referenced 10overall that prints a continuous web 12. This printing system isequipped with a traditional device for threading the continuous web 12and is disclosed by DE-A 198 01 317 of the same assignee. Variouscomponents that are also significant for the present system areexplained on the basis of this known printing system. The problem forthe present system is also illustrated.

The printing system 10 has a printer module 14 with integrated paperinput 16 as well as a fixing module 18 with paper output 20. A supplyreel 22 for the continuous web 12 is arranged preceding the paper input16, this being generally a paper web and being rotatably seated in apreprocessing device (not shown). A stack of a fan-fold web can also beoffered as a supply for the continuous web 12 instead of the supply reel22.

As viewed in a transport direction of the continuous web 12, a take-upreel 24 that is seated in a post-processing unit (not shown) is providedfollowing the paper output 20. Instead of the take-up reel 24, afinishing unit can also be connected to the paper output 20, this, forexample, further-processing the continuous web 12 by cutting.

Two deflection drums 26 and 28 as well as a paper drive 30 are arrangedin the printer module 14. Further, a printing device is provided in theprinter module 14, but this is not shown for the sake of clarity. Thefixing unit (not shown) as well as a driven haul-off 32 are arranged inthe fixing module 18, the haul-off 32 conveying the continuous web 12through the printing device 10 in common with the paper drive 30.

An insertion device—schematically referenced with 34—is also provided inthe printing system, the continuous web 12 being automaticallyintroduced into the entire printing system 10 therewith before beingprinted. For this purpose, the insertion device 34 employs two endlesscables 36 arranged at both sides of the transport path of the continuousweb 12, only one thereof being indicated by a dot-dash line in FIG. 1.The two cables 36 are conducted around a plurality of deflectionarrangements 40, 42, 44 and 46 along the transport path of thecontinuous web 12 through the printing system 10. The deflectionarrangements 40 and 42 are provided close to the deflection drums 26 and28. The deflection arrangement 44 is arranged close to the paper drive30, and the deflection arrangement is arranged close to the haul-off 32.Further, three deflection arrangements 48 are provided under the paperinput 16, these tensing the cables 36 in the region of the paper input16 and supplying them to the first deflection arrangement 40. The cabledrive 50 of the insertion device 34, which can be driven both in aforward as well as in a reverse rotational sense, is arranged under thepaper output 20. A cable tenser 52 that pre-stresses the two cables 36independently of one another is provided between the cable drive 50 andthe lower deflection arrangements 48.

Further, the insertion device 34 has a gripper device 54 proceedingtransverse to the transport path of the continuous web 12, the gripperdevice 54 being secured to the cables 36 with connector elements. Duringthe insertion of the continuous web, the gripper device 54 holds theleading edge thereof and is moved along the transport path by the cables36 in order to transport the continuous web 12 through the printingsystem 10. The cable drive 50 can move the gripper device 54 between theposition A close to the paper input 16 and the position B at thedeflection arrangement 46. The cable 36 is continuous and has a lengthcorresponding to the dot-dash line in FIG. 1.

When, given the printing system 10 of FIG. 1, the fixing module 18 isdetached from the printer module 14, then the cables must bede-installed. Given a later joining of fixing module 18 and printermodule 14, these cables 36 must be introduced anew and tensed. Since theprinter module 14 and the fixing module 18 respectively contain acomplex mechanism, the introduction of the cables 36 involves greatexpense. Moreover, the flexibility of the printing system 10 of FIG. 1is limited, since the fixing module 18 and the printer module 14 are notmodularly constructed in view of the insertion device 34.

FIG. 2 shows an exemplary embodiment. A printer module 60 of ahigh-performance printing system is detachably connected to a fixingmodule 62 at an interface 64. The two modules 60, 62 are transported toa customer separately from one another and are assembled thereat at theinterface 64. As the respective traction unit 66 or 68, each module 60,62 respectively contains two separate cables one each of which is arearranged at the opposite long sides of the transport path of thecontinuous web 12. For reasons of clarity, the transport path for thecontinuous web 12 is not shown in detail in FIG. 2; similar to FIG. 1,however, it proceeds from an input section 70 of the first module 60 upto an output section 72 of the second module 62 along transport rollers74 for the continuous web 12, to which deflection elements 76 areallocated for guiding the cables 66, 68. A gripper device 78 can bemoved from the input section 70 up to the output section 72 by thecables 66 and 68. As shall be described in greater detail later, thegripper device 78 grips a beginning section of the continuous web 12 andtransports this beginning section from the input section 70 of the firstmodule 60 up to the output section 72 of the second module 62.

As a drive unit, a first stepping motor 80 is arranged within theprinter module 60, said first stepping motor 80 driving a first wind-updrum 82 onto which the two cables 66 are wound or from which the cables66 are unwound.

In the same way, a second stepping motor 84 in the fixing module 62 isconnected to a second wind-up drum 86 that winds up or unwinds thecables 68. The two stepping motors 80, 84 are preferably drivensynchronously with one another, i.e. the wind-up or unwinding of thecables 66, 68 occurs synchronously. Alternatively, other motors that canbe exactly positioned can also be employed, for example motors withincremental sensors that are driven incrementally.

The printer module 60 contains a tensing unit 88 with position sensorsfor each cable of the cable pair 66. In the parted condition of themodules 60, 52, this tensing unit 88 generates a cable tension for thecable 66. In the connected condition of the modules 60, 62, this tensingunit 88 generates the required cable tension for the cables 66, 68(which are then connected) and also serves for the control of thestepping motors 80, 84 with the assistance of the control module 90.

A first monitoring unit 92 and a second monitoring unit 94 that areconnected to control modules 96 or 98 are provided in the fixing module62 for each of the two cables 68. The first monitoring unit 92 monitorsthe cable 68 for upward transgression of a maximum tensile stress. Thesecond monitoring unit 94 monitors the cable 68 for downwardtransgression of a minimum tensile stress. The monitoring units 92, 94respectively contain a position sensor, for example a micro switch, thatmonitors the position of a spring-loaded deflection drum around whichthe respective cable 68 is conducted. Given upward transgression of themaximum tensile stress or downward transgression of the minimum tensilestress, the position of the spring-loaded deflection roller changes,this being signaled to the control modules 96, 98 by the micro switch.With the assistance of the monitoring units 92, 94, an overload, forexample due to a blockage of the cables 66, 68, or an under-load, forexample when the continuous web or the cables 66, 68 tear, is recognizedand signaled as an operating error. In the case of separated modules 60,62, the monitoring units 92, 94 also offer the required cable tensionfor the cables 68 in the module 62.

It should also be mentioned that the control modules 90, 96 and 98 arepreferably realized in software terms. A controller evaluates thesupplied signals and generates the necessary displays or necessarycontrol commands.

In a schematic drawing, FIG. 3 shows the interface 64 between the twomodules 60, 62 in various operating phases. In the upper part of theFigure, the two modules 60, 62 reside opposite one another with the tworespective cables 66, 68. The cables 66, 68 are connected to one anotherat a connector device 100. This connector device 100 also carries thegripper device 78, as shall be explained in greater detail later.

The structure of the connector device 100 can be seen in the middle partof FIG. 3. The connector device 100 contains a first crossbeam 102 and asecond crossbeam 104 that can be connected to one another or detachedfrom one another at a parting surface 106. The crossbeams 102, 104 havespecifically shaped form elements 108, 110 at their ends that serve thepurpose of guiding the connector device 100—that also carries thegripper device 78 at the same time—jerk-free on its path through the twomodules 60, 62. The two form elements 108, 110 can likewise be separatedat the parting surface 106. It must be pointed out that the gripperdevice 78 can also be arranged separate from the connector device 100.

The two cables 68 (only one can be seen in FIG. 3) of the fixing moduleare detachably fastened to the second crossbeam 104 in a fasteningopening 114. Likewise, the two cables 66 of the printer module 60 aredetachably fastened in fastening openings 112 of the first crossbeam102. For example, the cables 66, 68 are hooked into the fasteningopenings 112, 114 with clamping sleeves secured to them. In theirconnected condition, the two crossbeams 102, 104 are connected to oneanother with fastener elements, for example screws (not shown).

The lower part of FIG. 3 shows the condition wherein the two modules 60,62 are detached from one another. The two crossbeams 102, 104 of theconnector device 100 are detached from one another at the parting line106, for example by unscrewing the connecting screws. The firstcrossbeam 102 is accepted in a first mounting 61 and is swiveled up inthe direction of the arrow 116 around a swiveling axis 118 within theprinter module 60. In this way, the first crossbeam 102 is acceptedwithin the module 60 such that it does not project beyond the limitingplane of the module 60 that faces toward the fixing module 62. Theswivel around the swiveling axis occurs such that the cable 66 remainsessentially length-neutral, i.e. no additional cable path is required asa result of the swivel motion. The second crossbeam 104 is also held ina second mounting 63 in the fixing module 62 such that it does notproject beyond the limiting plane of the module 62 that faces toward theprinter module 60. The cables 66, 68 remain anchored in the fasteningholes 112, 114 and are kept under tension by cable tensioning devices inthe respective modules 60, 62. In the detached condition of the modules60, 62, the crossbeams 102, 104 are arrested in the respective mountings61, 63.

The swiveling of the first crossbeam 102 has a further advantage. Apossible, slight prescribed distance between the two modules 60, 62 canbe bridged by the length of the swivel arm, this being preferablyadjustable. As an alternative to a swivel motion, however, it is alsopossible in another exemplary embodiment to translationally move the twocrossbeams 102, 104 toward one another. As warranted, a length store forthe cables 66 or 68 is then required.

For connecting the two modules 60 and 62, the crossbeam 102 is swiveledaround the swiveling axis 118 toward the second crossbeam 104 in themodule 62 opposite the arrow direction 116. The two crossbeams 102 and104 are subsequently connected to one another. After this, the arrestsfor the crossbeams 102, 104 are undone, so that the two connectedcrossbeams 102, 104, pulled by the cables 66, 68, can move freelythrough the two modules as connector device 100 with the gripper device78.

For detaching the modules 60, 62 from one another, the connector device100 is moved to the module boundary, so that the crossbeams 102, 104 arepositioned relative to the mountings 61, 63. The crossbeams 102, 104 arearrested in these mountings 61, 63. Since the cables 66, 68 in eachmodule 60, 62 are also under tensile stress in the separated condition,no loose ends of the traction elements derive at the interface. Thecables 66, 68 thus assumed a defined, stable operating condition, as aresult whereof operating errors are avoided.

The required handling for connecting the two crossbeams 102, 104 to oneanother and for releasing the two crossbeams 102, 104 from one anotherensues such that corresponding actuation elements are actuatedproceeding only from the side of the module 60. These actuation elementscannot be reached proceeding from the side of the module 62. Thehandling with the connector device 100 is facilitated in this way sincean operator need only implement work steps proceeding from one module.

FIG. 4 shows a perspective view of the two crossbeams 102 and 104 in acondition detached from one another. The second crossbeam 104 accepts aplurality of gripper elements 120, only one thereof being shown in FIG.4. The totality of gripper elements 120 forms the gripper device 78,which is thus carried overall by the connector device 100. The gripperelements 120 fit in openings 124 in the first crossbeam 102. Eachgripper element 120 has a mouth-shaped opening 122 for accepting thebeginning section of the continuous web 12. This beginning section isheld clamped in the gripper elements 120, so that it can be transportedthrough the modules 60, 62.

FIG. 5 shows an essential part of the tensing unit 88 (see FIG. 2). Whatis shown is a deflection roller 130 that guides the cable 66 in a wrapangle of approximately 180°. The deflection roller 130 has a roller axle132 that is guided on a roller 138 in a longitudinal guide 134displaceable along a longitudinal axis together with a movable carriage136. The longitudinal guide 134 is let into legs 140 of a mounting 142.The roller axle 132 is pre-stressed in the direction of the axis 146 bytension springs 144. Alternatively, the pre-stress can also be generatedby a compression spring that then correspondingly influences thedeflection roller 130. Two Hall generators 148, 150 that interact with aplurality of permanent magnets (two thereof are referenced 152) arearranged on a leg 140. The permanent magnets 152 are moved together withthe movable carriage 136 given excursion of the deflection roller 130.Together with the Hall generators 148, 150, the magnets 152 formposition sensors that signal the excursion of the deflection roller 130.Preferably, the magnets 152 are arranged such that the Hall generators148, 150 signal a minimum or a maximum excursion of the deflectionroller 130. These signals proceed to the control module (see FIG. 2) andare evaluated thereat for the control of the stepping motors 80, 84.Instead of the arrangement comprising a plurality of permanent magnets152 shown in FIG. 5, an arrangement having a single, elongated permanentmagnet can also be employed, the effective magnetic field thereofinfluencing both Hall generators 148, 150 in the normal operatingposition of the deflection roller 130.

FIG. 6 schematically shows four conditions of the deflection roller thatare reproduced by the signals of the Hall generators 148, 150 givenemployment of an elongated permanent magnet. These signals are evaluatedby the control module 90 (see FIG. 3), which in turn has a controllinginfluence on the stepping motors 80, 84.

In condition ‘a’, the deflection roller 130 and the carriage 136 withthe permanent magnet is in a normal position wherein both Hallgenerators 148, 150 acquire the magnetic field of the permanent magnet.In condition ‘b’, the deflection roller 130 is deflected upward in afirst position on one occasion and deflected downward in a secondposition on another occasion. Both positions are just still acquired attheir limits by the Hall generators. In condition ‘c’, the respectiveexcursion upward or downward is so great that only one Hall generator148 or 150 still acquires the respective position. In condition ‘d’, thedeflection roller 130 is deflected upward or downward so far that therespective acquisition range of the Hall generators 148 or,respectively, 150 is left.

In conditions ‘a’ and ‘b’, the signals output by the Hall generators148, 150 produce no additional regulation of the stepping motors 80, 84.In condition ‘c’, the signals result therein that a regulatingintervention is performed on the stepping motors 80, 84. In condition‘d’, there is an error case that is signaled by the signals of the Hallgenerators.

In the example according to FIG. 2, a first monitoring unit 92 and asecond monitoring unit 94 is provided in the fixing module 62 for eachcable 66. Proper operation is monitored with the assistance of controlmodules 96 and 98 allocated to them. When a maximum tensile stress, forexample a cable tension greater than 100 N, is detected, then a microswitch contained in the monitoring unit 92 is triggered. The controlmodule 96 then switches the motors 84 and 80 off. When the secondmonitoring unit 94 detects the downward transgression of a minimumtensile stress, for example when the paper web tears, then a microswitch is likewise triggered. The allocated control module 98 thencauses a stoppage of the motors 84, 80. For example, the motor stop istriggered given downward transgression of a cable tension less than orequal to 12 N. What is achieved in this way is that an improperoperation does not lead to damage. When, for example, the gripper device78 is blocked, then the cable tension rises rapidly. The shut-off of themotors 80, 84 prevents damage to the apparatus. When the tensile forcein the cable is too low, for example given a torn cable or when one ofthe cables sags, then the forward transport of the cables 66 mustlikewise be shut off and an error message output, since no controlledguidance of the gripper device 78 is possible in this operatingcondition.

FIGS. 7 through 10 show an exemplary embodiment of a combined monitoringdevice 160 that unites the functions of the monitoring units 92, 94 in asingle device. Identical parts are referenced the same.

The monitoring device 160 shown in FIG. 7 has a U-shaped frame 162 witha base 164 and two legs 166, 168. These legs 166, 168 of the frame 162contain oblong holes 170 at both sides in which respective pegs 172 areguided (only one peg 172 can be seen in FIG. 7) or a single, continuouspeg 172 projects into both oblong holes 170. A first tension spring 174attacks at the peg 172 or tension springs attack at both sides for agreat cable force that pulls the peg 172 in the direction of a furtherpeg 176 rigidly connected to the leg 168. The peg 172 is connected to afirst carriage 178 designed U-shaped that serves as the first tensingdevice. The first carriage 178 has a respective oblong hole at its twolegs in which a respective peg 182 or a continuous peg 182 is guided. Atboth legs, this peg 182 is preferably respectively connected to the endof a second tension spring 184 for low cable force that is rigidlyconnected via a further peg 186 to the first carriage 178. The peg 182movable within the oblong hole 180 is rigidly connected to a secondcarriage 188 serving as the second tensing device that carries thedeflection roller 130 on the shaft 132. An oblong hall magnet 190 isarranged at the second carriage 188. A Hall sensor 192 is arranged onthe second leg 168 of the frame 162. Given an excursion motion of thedeflection roller 130, the relative position of Hall magnet 190 to Hallsensor 192 is modified.

A guide peg 194 (only partly visible) that is rigidly connected to thefirst carriage 178 engages into the oblong hole 170. The guide peg 192lies against a detent 196 and thus limits the movement of the firstcarriage 178 in the direction of the base 164. The second carriage 188likewise carries a guide peg 198 that is guided in the oblong hole 180.Its movement toward the left is limited by a detent (not shown) in theoblong hole 180. A detent 200 [and [sic]] limits the longitudinalmovement of the second carriage 188 relative to the first carriage 178.In the illustrated, normal operating position, the peg 182 lies againstthe detent 200. The guide peg 194 likewise lies against the detent 196.This means that the first tension spring 174 presses the first carriage178 in the direction of the base 165 up to the detent 196; a cable (notshown) guided around the deflection roller 130 has such a high tensileforce on the deflection roller 130 that the second carriage 188experiences maximum excursion in the direction in FIG. 7 toward theright, and the peg 182 lies against the detent 200. The tensile force ofthe first tension spring 174 is greater in this condition than thetensile force of the cable that acts on the deflection roller 130. Thetensile force of the second tension spring 184 is lower than the tensileforce of the cable.

When the cable force with which the cable pulls toward the right at thedeflection roller 130 in FIG. 7 falls below a specific value, forexample 15 N, then the second tension spring 184 pulls the secondcarriage 188 and the deflection roller 130 in the direction of the baseand thereby tenses the cable. When the cable force continues to drop,for example below 12 N, then the Hall magnet 190 on the second carriage188 is moved so far in the direction of the base that it travels out ofthe coverage area of the Hall sensor 192. The Hall sensor 192 signalsthis condition, whereupon the motors 80, 84 are stopped and thetransport of the gripper device 78 is interrupted. This condition canoccur, for example, when the guided cable rips. When the cable forcethat acts on the deflection roller 130 rises above a specific value, forexample 90 N, then the first tension spring 174 is tensed and the peg172 experiences maximum excursion in the direction of the deflectionroller 130 up to the detent 173, whereby the cable will yield. When thecable force continues to rise, for example above 100 N, then the Hallmagnet 190 reflecting the position of the deflection roller 130 willmove out of the coverage area of the Hall sensor toward the right, as aresult whereof a corresponding signal is triggered that stops the motors80, 84. The transport of the gripper device 78 is thereby stopped. Thisoperating condition can occur when the gripper device has its transportblocked.

The position of the Hall sensor 192 relative to the Hall magnet 190 andthe length of the Hall magnet 190 define the path length of the coveragearea for the second carriage 188 relative to the stationary frame 162and thus also define the cable path within which a proper operatingcondition is signaled. When the coverage area is left, then an errorcondition is signaled. This coverage area can be varied by changing theposition of the Hall sensor 192 or by changing the length of the Hallmagnet 190.

FIG. 8 shows various operating conditions of the monitoring unit 160.The leg 168 of the frame 162 contains oblong holes 202 in the directionof the axis of the cable 66. With the assistance of these oblong holes202, the frame 162 can be mounted rigidly to the device in the module 62(see FIG. 2), so that an adaptation to the cable length of the cable 66can be achieved by a simple shifting of the frame 162. The normaloperation of the monitoring unit 160 is shown in the upper part of FIG.8. The excursion of the deflection roller 130 is illustrated on thebasis of the reference axis 204. The cable tension in the cable 66 istoo low in the middle part of the Figure; the deflection roller hasdeflected toward the left from the reference axis 204. The peg 182 nolonger lies against the detent 200. The Hall magnet 190 leaves thecoverage area of the Hall sensor 192, which signals this operatingcondition.

The cable tension of the cable 66 is too high in the lower part of FIG.8. The deflection roller 130 has deflected toward the right from thereference axis 204. The tension spring 174 for high cable force istensed and the peg 172 is deflected toward the right. The Hall magnet190 leaves the coverage area of the Hall sensor 192 toward the right andthe latter signals this error condition.

The combined monitoring unit 160 according to FIGS. 7 and 8 can alsoadditionally assume the function of the cable tensioning for the cable66. For this purpose, it is necessary that at least one peg 182 or 194does not lie against the allocated detent 200 or 196 within a regulatingregion for tensing the cable. FIG. 9 shows the regulation of the cabletension on the basis of a diagram. The shaft 132 of the deflectionroller 130 can move back and forth within a regulating region 210,whereby a pre-defined cable tension is offered by the combined springpower of the first tension spring 174 and the second tension spring 184.The two springs are symbolically shown as one spring F in FIG. 9. Theentered position 212 of the shaft 132 references a rated position withinthe regulating region 210. When the cable tension slackens, the shaft132 moves toward the left in FIG. 9. This movement toward the left iseffected by the second tension spring 184, whose spring path is definedby the arrow F1 between a first position 214 and a second position 216.The first position 214 is determined by the detent of the peg 182 at thedetent 200. The second position 216 is defined by a detent of the guidepeg 198 within the oblong hole 180 (not shown in FIG. 7). A path 218 isprovided outside the regulating region 210 within which the motors 80,84 (see FIG. 2) are to be shut off.

When the cable tension in the cable 66 becomes too great, then the shaft132 of the deflection roller 130 in FIG. 9 is moved toward the right.When the position 214 is reached and overcome—the guide peg 182 lyingagainst its detent 200 thereat B, then the first tension spring 174 isdeflected. In FIG. 9, the spring path of this first tension spring 174between the position 214 and the position 220 is referenced F2. Theposition 220 is defined by the peg 172 lying against the detent 173. Ashut-off path 222 when leaving the regulating region 210 derivestherefrom. The assembly composed of Hall magnet 190 and Hall sensor 192as well as the additional control elements must be designed such that adependable shut-off of the motors 80, 84 occurs within the path 222. Inthe normal condition, these motors 80, 84 are driven such that the shaft132 remains within the regulating region 210. The position of the shaft132 is thereby signaled by the arrangement of Hall magnet 190 and Hallsensor 192. The motors 80, 84 are then correspondingly driven within acontrol loop. In order to prevent an unnecessarily high cable tension inthe cable 66, the rated position 212 of the shaft 132 of the deflectionroller 130 should be selected such that the second tension spring 184with the low spring power is at a relatively small distance, typically 5through 10 mm, from the right detent, i.e. the distance between thepositions 212 and 214 is to be correspondingly selected.

FIG. 10 schematically shows a modification wherein compression springs206 and 208 are employed instead of the tension springs 174 and 184. Inthis modification, the cable 66 that is guided around the deflectionroller 130 need not be threaded through into the space between secondcarriage 188 and deflection roller 130. Simpler handling upon insertionof the cable 66 is thus possible.

The first compression spring 206 for high cable force attacks at thesecond carriage given the example according to FIG. 10, so that the peg182 lies against the detent 200 during normal operation. The secondcompression spring 208 for low cable force attacks at the peg 172, thisbeing shown in its maximum left-hand position in FIG. 10. When the cableforce in the cable 66 is reduced, then the deflection roller 130 and thepeg 172 moves toward the right in FIG. 10. When the cable force becomestoo high, then the deflection roller 130 and the peg 182 moves towardthe left in FIG. 10. The dislocation of this position in the example ofFIG. 7 is signaled by the arrangement comprised of Hall magnet 190 andHall sensor 192.

Additionally, let it be pointed out that leaf springs or other springelements can also be employed for realizing the spring tension for thetwo carriages.

While a preferred embodiment has been illustrated and described indetail in the drawings and foregoing description, the same is to beconsidered as illustrative and not restrictive in character, it beingunderstood that only the preferred embodiment has been shown anddescribed and that all changes and modifications that come within thespirit of the invention both now or in the future are desired to beprotected.

1. An apparatus for threading a continuous web, comprising: a firstmodule and at least one second module connectable to and detachable fromone another at an interface and which are successively traversed by thecontinuous web; respective first and second traction units withcorresponding drive units being provided in the first and secondmodules; a gripper device for gripping a beginning section of thecontinuous web and attachable to the traction units, the continuous webbeing pulled with the assistance of said gripper device from an inputsection to an output section of the respective module given movement ofthe traction units; a connector device with which the traction units ofthe two modules residing opposite one another at the interface areconnectable to and detachable from one another; and the gripper devicetransporting a beginning section of the continuous web from the inputsection of the first module up to the output section of the secondmodule in the connected condition of the traction units.
 2. Theapparatus according to claim 1, wherein the first traction unit of thefirst module and the second traction unit of the second module eachcomprise two traction elements respectively arranged at opposite longsides of a transport path of the continuous web.
 3. The apparatusaccording to claim 2 wherein one of a cable, a chain and a band isprovided as each traction element.
 4. The apparatus according to claim 1wherein the connector device contains a first crossbeam and a secondcrossbeam connected to the first traction unit and to the secondtraction unit respectively, the two crossbeams are detached from oneanother in the detached condition of the modules, and the two crossbeamsare connected to one another in the connected condition of the twomodules.
 5. The apparatus according to claim 4 wherein the respectivecrossbeams are accepted in the modules in the detached condition of themodules such that they do not project beyond a limiting plane of themodules facing toward one another.
 6. The apparatus according to claim 4wherein at least one of the crossbeams is seated swivellable around aswiveling axis, a swiveling of the crossbeam occurring substantiallylength-neutral for the respective traction unit.
 7. The apparatusaccording to claim 4 wherein the respective crossbeams are arrested intheir position in the detached condition of the modules.
 8. Theapparatus according to claim 4 wherein mechanical actuation elementscorresponding to one another are actuated from a side of only one modulefor connecting the two crossbeams.
 9. The apparatus according to claim 1wherein the connector device holds the gripper device.
 10. The apparatusaccording to claim 9 wherein the gripper device contains one or moregripper elements that clamp a beginning section of the continuous web.11. The apparatus according to claim 1 wherein each module contains atleast one tensing unit that keeps the respective traction unit undertension.
 12. The apparatus according to claim 11 wherein the tensingunit contains a deflection roller around which the traction unit isconducted, and the deflection roller is seated displaceable along alongitudinal axis and is pre-stressed in a direction of the axis by aspring unit.
 13. The apparatus according to claim 12 wherein the tensingunit contains a position sensor that acquires a position of thedeflection roller relative to the longitudinal axis.
 14. The apparatusaccording to claim 13 wherein the position sensor contains a firstposition sensor and a second position sensor that signal an excursion ofthe deflection roller.
 15. The apparatus according to claim 14 whereinthe first and the second position sensors comprise a Hall generator thatinteracts with at least one permanent magnet.
 16. The apparatusaccording to claim 1 wherein the first module and the second modulerespectively contain a drive unit that winds the respective tractionunit onto a wind-up reel or unwinds the traction unit from the wind-upreel.
 17. The apparatus according to claim 16 wherein a stepping motoris employed as the respective drive unit.
 18. The apparatus according toclaim 17 wherein the drive units in the first and in the second modulesare synchronously driven.
 19. The apparatus according to claim 16 whereboth drive units are controlled by signals of the position sensors. 20.The apparatus according to claim 1 wherein a first monitoring unitmonitors at least one of the traction units for upward transgression ofa maximum tensile stress.
 21. The apparatus according to claim 1 whereina second monitoring device monitors at least one of the traction unitsfor downward transgression of a minimum tensile stress.
 22. Theapparatus according to claim 21 wherein the first and the secondmonitoring units respectively contain a position sensor that monitors aposition of a spring-loaded deflection roller around which the tractionunit is conducted.
 23. The apparatus according to claim 1 wherein acombined monitoring device is provided that monitors at least one of thetraction units for upward transgression of a maximum tensile stress aswell as for downward transgression of a minimum tensile stress.
 24. Theapparatus according to claim 23 wherein the combined monitoring devicecontains a frame in which a first tensing unit is arranged displaceablein its longitudinal axis against a force of a first spring; the firsttensing unit contains a second tensing unit seated displaceable in alongitudinal direction against a force of a second spring, said secondtensing unit seating a deflection roller around which the traction unitis guided; and a position of the deflection roller is. determined by aposition sensor that triggers an error signal given upward transgressionof a prescribed limit position value.
 25. The apparatus according toclaim 24 wherein the force of the first spring is dimensioned in thenormal operating condition such that the first tensing unit is held in afirst limit position in stable fashion; and the force of the secondtension spring is dimensioned such that the second tensing unit is heldin a second limit position in stable fashion.
 26. The apparatusaccording to claim 25 wherein the force of the first spring isconsiderably greater than a force of the traction unit acting on thedeflection roller; and the force of the second spring is dimensionedsuch that it is considerably lower than the force of the traction unitacting on the deflection roller.
 27. The apparatus according to claim 25wherein the position sensor signals a departure from the limit positionsof a first thrust unit or of a second thrust unit.
 28. The apparatusaccording to claim 24 wherein the position sensor contains a Hall magnetand a Hall sensor.
 29. The apparatus according to claim 28 wherein onecomponent of the position sensor is arranged at a frame and the othercomponent is arranged on the second tensing unit.
 30. The apparatusaccording to claim 28 wherein the Hall sensor has a coverage area forthe Hall magnet, and an error signal is triggered given departure fromthe coverage area.
 31. The apparatus according to claim 23 wherein fortensing the traction unit, an actual position of the deflection rolleris acquired, the deflection roller is regulated within a regulatingregion by driving drive units, and an error signal is generated givendeparture from the regulating region.
 32. The apparatus according toclaim 24 wherein a compression spring is respectively employed as thefirst and second springs.
 33. The apparatus according to claim 1 whereina displacement unit is provided at a frame with which the frame isdisplaceable relative to a rigid frame in order to adapt a combinedmonitoring unit to a length of the traction unit.
 34. The apparatusaccording to claim 1 wherein the first module is one of a printer moduleand a copier module and the second module is a fixing module containinga fixing facility.
 35. A printing or copying system, comprising: a firstmodule containing a printing device and at least a second modulecontaining a fixing device connectable to and detachable from the firstmodule at an interface; a traction unit provided in each module and agripper device for gripping a beginning section of a continuous web tobe transported from an input section up to an output section of therespective module; and a connector device with which the traction unitsof both modules residing opposite one another at the interface areconnectable to and detachable from one another so that in the connectedcondition of the traction units, the gripper device transports thebeginning section of the continuous web from the input section of thefirst module up to the output section of the second module.
 36. Aprinting or copying system module, comprising: a connecting systemconnecting and detaching the module from a further module at aninterface; a traction unit arranged in the module with assistance ofwhich a gripper device for gripping a beginning section of a continuousweb is transported from an input section up to an output section of themodule; and a connector device with which the traction unit of themodule is connected and detached from a traction unit in the furthermodule.
 37. A module according to claim 36 including: a monitor formonitoring a tension of the traction unit which transports the beginningsection of the continuous web which is attached to the traction unitwith the gripper device; and the monitor monitoring whether said tensionexceeds a maximum tensile stress or falls below a minimum tensilestress.
 38. The monitoring device according to claim 37 wherein a frameis provided in which a first tensing device is arranged displaceable onits longitudinal axis against a force of a first spring; the firsttensing device containing a second tensing device seated displaceable inthe longitudinal direction against a force of a second spring saidsecond tensing device seating a deflection roller around which thetraction unit is guided; and a position of the deflection roller beingdetermined by a position sensor that triggers an error signal givenupward transgression of a prescribed limit position value.
 39. Themonitoring device according to claim 38 wherein the force of the firstspring is dimensioned in a normal operating condition such that thefirst tensing device is held in a first limit position in stablefashion; and the force of the second tension spring is dimensioned suchthat the second tensing device is held in a second limit position instable fashion.
 40. The monitoring device according to claim 39 whereinthe force of the first spring is considerably greater than the force ofthe traction unit acting on the deflection roller; and the force of thesecond spring is dimensioned such that it is considerably lower than theforce of the traction unit acting on the deflection roller.
 41. Themonitoring device according to claim 40 wherein the position sensorsignals a departure from the limit positions of the first thrust deviceor of the second thrust device.
 42. The monitoring device according toclaim 41 wherein the position sensor contains a Hall magnet and a Hallsensor.
 43. The monitoring device according to claim 42 wherein the Hallsensor has a coverage area for the Hall magnet, and an error signal istriggered given departure from the coverage area.
 44. The monitoringdevice according to claim 38 wherein one component of the positionsensor is arranged at the frame and another component is arranged on thesecond tensing device.
 45. The monitoring device according to claim 38wherein for tensing the traction unit, an actual position of thedeflection roller is acquired, the deflection roller is regulated withina regulating region by driving the drive units, and an error signal isgenerated given departure from the regulating region.
 46. The monitoringdevice according to claim 38 wherein a compression spring isrespectively employed as the first and the second spring.
 47. Themonitoring device according to claim 37 wherein a frame is displaceablerelative to a rigid frame of the device in order to adjust a combinedmonitoring unit to a length of the traction unit.
 48. An apparatus forthreading a continuous web, comprising: a first module and a secondmodule connectable to and detachable from one another at an interfaceand which are successively traversed by the continuous web; respectivefirst and second traction units provided in the first and secondmodules; a gripper device for gripping a beginning section of thecontinuous web and attachable to the traction units, the continuous webbeing pulled with the assistance of said gripper device from an inputsection to an output section of the respective module given movement ofthe traction units; a connector device connected with the gripper deviceand with which the traction units of the two modules residing oppositeone another at the interface are connectable to and detachable from oneanother; and the gripper device transporting a beginning section of thecontinuous web from the input section of the first module up to theoutput section of the second module in the connected condition of thetraction units.
 49. A method for threading a continuous web into adevice comprising a first module and at least one second moduleconnectable to and detachable from one another at an interface and whichare to be successively traversed by the continuous web, comprising thesteps of: providing respective first and second traction units in thefirst and second modules; attaching the first module to the secondmodule, attaching the first traction unit to the second traction unitwith a connector device, and providing a gripper device connected to theconnected first and second traction units; connecting a beginningsection of the continuous web to the gripper device; and moving theconnected first and second traction units so as to pull the continuousweb from an input section of the first module up to an output section ofthe second module.
 50. The method according to claim 49 including thestep of providing the gripper device and the connector device together.51. The method according to claim 49 including the step of providing aseparate drive unit in the first module for driving the first tractionunit and another drive unit in the second module for driving the secondtraction unit.